1. Field of the Invention
The present invention generally relates to a method and apparatus for treating the surface of a body of liquid, and more specifically to a method and apparatus for treating the surface of a solar pond.
2. Discussion of Prior Art
Liquid evaporation is conventionally retarded by spreading paraffin oil on the surface of the liquid to form a static film that also inhibits wave formation.
British Pat. No. 348,729 discloses the use of an oil film on a reservoir for reducing heat loss through evaporation.
Reiser, U.S. Pat. No. 3,528,764, discloses apparatus for spraying oil on the surface of a body of water to retard evaporation and suppress wave formation. This apparatus comprises a spray or battery of sprays which are wind activated so that a film of oil placed on the water surface will always be applied on the upwind side. A change in wind direction moves the film downwind on the water surface and directs automatic spraying upwind of the new wind direction.
Treloar et al., U.S. Pat. No. 2,878,098, disclose apparatus for retarding evaporation from reservoirs or other water storage areas. The apparatus includes a plurality of posts driven into the bank of a water storage area which serve as anchors for wind operated valves which disperse a protective liquid onto the upper surface of the body of water.
Florey et al., U.S. Pat. No. 3,184,789, disclose apparatus for spraying a retardant such as a fatty alcohol on the surface of a body of water to reduce evaporation. Spray nozzles, regulated by solenoid-operated valves, which are in turn connected to a wind-operated switch, spray the retardant onto the water surface only when the wind is operative within a 90 degree arc, and are intermittently actuated to cause retardant to be applied to the liquid surface in short bursts.
British Pat. No. 898,431 discloses apparatus for establishing a suspension and/or emulsion of fatty alcohol and water for retarding water evaporation. The composition is dispersed by a sprayer in droplet form over the water, the wind direction being utilized to distribute the retardant in a desired direction.
Koberg, U.S. Pat. No. 3,425,791, discloses apparatus for distributing fatty alcohol on the surface of a reservoir to retard evaporation. The apparatus includes a control valve which is responsive to the rotation of a wind vane, and, accordingly, to changes in wind direction, in order to control the amount of suppressor liquid dispensed at predetermined intervals for appropriately covering the surface of the reservoir.
Fox, U.S. Pat. No. 3,431,063, discloses the utilization of hydrocarbon oils spread over a water surface in order to retard evaporation. Similarly, Cashman, U.S. Pat. No. 3,458,274, discloses the utilization of wax and hydrocarbon oil blends to be dispersed over the surface of an open reservoir to retard loss due to evaporation.
A basic problem with the conventional approaches described above is that they do not remove air-borne dust particles and other debris which collect on the film and float on the surface. In a solar pond environment, this situation is undesirable because the particles are either reflective and reduce the efficiency of the pond as a collector of solar radiation or absorb radiation at the interface where the heat is dissipated to the atmosphere by the convective nature of the windmixed layer at the surface.
Accordingly, it is a general object of the present invention to provide a new and improved method and apparatus for coating the surface of liquid with oil which overcomes or substantially reduces the problems associated with the prior art.